1. Field of the Invention
The present invention relates to a system for automatically and periodically discharging a quantity of spray from an aerosol container. More specifically, the present invention relates to an automatic aerosol dispensing system in which the nozzle of the aerosol container is maintained in a fixed position during operations.
2. Description of the Prior Art
Pressurized aerosol containers have achieved wide usage in dispensing materials such as deodorizers, insecticides, germicides and the like. Such containers are commonly provided with an upwardly projecting valve having a spray nozzle. The valve may be opened with downward pressure, or in some cases, or in some cases, by tilting the valve to one side. There are two basic types of values. One type provides a continuous spray as long as the valve is depressed, and the other type provides a single metered spray upon depression of the valve.
There are numerous applications in which it is advantageous to automatically and periodically actuate the valve of an aerosol container to dispense a predetermined quantity of spray at periodic timed intervals. There are also numerous automatic dispensers presently on the market. Devices of this kind are commonly provided with an electric motor with means for periodically actuating the valve. Other devices of this kind operated with motors which are energized by high voltage alternating current at the usual line potential. Consequently, it is necessary to provide a line cord for connecting such device to the alternating current source. When it is desired to place the device in a location where there is either no nearby outlet or whereby the provision of a line cord would be objectionable, battery electrical power sources are to be employed.
Devices for driving a DC motor from batteries to accomplish a periodic actuation from an aerosol container are also well known. For example, U.S. Pat. No. 3,543,122 discloses an automatic aerosol dispenser wherein a DC motor drives a gear which, in turn, is coupled by means of an eccentric drive to a valve actuator in the form of a ring. The eccentric drive includes a ball which is driven between the ring and a drum to drive the ring against the valve to emit a burst of spray. The ring is spring loaded so that upon reversal of the DC motor, as controlled by a separate reversing element, valve actuation is terminated.
Another DC motor driven automatic aerosol dispensing device is disclosed in the U.S. Pat. No. 3,289,886. In this patent a DC motor is shown connected through reduction gearing to a cam. The cam, in turn, is engaged by a cam follower which is coupled to a spring loaded valve-engaging element. The valve-engaging element is urged downwardly against the valve. When an undulation on the cam is rotated to an appropriate position by the DC motor, the valve-engaging element is released to depress the valve and a burst of spray is emitted. In additon, the output of the reduction gear train rotates a mechanical delay-switch which periodically energizes the motor for short time periods to rotate the cam 180.degree. for a valve actuation.
The automatic aerosol dispensing devices shown in U.S. Pat. Nos. 3,543,122 and 3,289,886 include mechanical elements which increase the complexity of the device. For example, the mechanical delays employed in both of these devices require additional structural features which are rotated by the motor. Additional mechanical elements such as the cam in U.S. Pat. No. 3,289,886 or the eccentric ball mount in U.S. Pat. No. 3,543,122 are necessary to actuate the output valve of an aerosol container. A spring loading feature employed in the dispenser of U.S. Pat. No. 3,289,886 presents an additional undesired force which must be overcome during rotation of the motor and thus, demands additional energy from the power supply.
In another type of periodically operated aerosol container, a motor may be employed which is continuously rotated on AC power, e.g., U.S. Pat. Nos. 3,018,056, 2,928,573 and 2,613,108.
In U.S. Pat. No. 2,928,573, valve is depressed by a flat metal plate connected to the output shaft of a reduction gear train driven by a synchronous AC motor. The motor is continuously operated, but when the metal plate contacts and depresses the metering valve, an automatic motor reversal occurs. As the flat metal plate is then rotated away from the valve, contact is made with a stop where another motor reversal arises to again advance the flat metal plate to the valve for its actuation. The automatic spray dispenser described in U.S. Pat. No. 3,018,056 utilizes a continuously driven cam to pivot a pair of valve-engaging links in sequence for a metered burst of spray.
Periodically operated solenoids are employed in automatic aerosol dispensers as described in the U.S. Pat. Nos. 3,351,240 and 3,187,949.
In U.S. Pat. No. 3,351,240, an electronic timing circuit generates an output pulse which turns an electronic transistor switch on for a time period sufficient to energize a solenoid whose armature is moved to permit the emission of a burst of spray. In U.S. Pat. Nos. 3,187,949 and 3,351,240, the armatures of the solenoids form an integral part of a modified valve. Such construction is complex and tends to demand excessive electrical power from limited power sources such as batteries.
U.S. Pat. No. 3,739,944 provides an automatic spray dispenser in which a DC motor is positively coupled by a reduction gear train and a valve contacting element to the nozzle portion of an aerosol container. The valve contacting element which normally rests upon the nozzle portion, depresses the nozzle portion upon motor actuation to thereby move the nozzle downwardly and open a spring loaded output valve. A timing circuit delivers pulses of electrical power from a battery power source to the motor. Motor rotation persists until the valve seats at the end of its stroke, and the DC motor is stalled towards the end of the power pulse. When power to the DC motor is terminated at the end of a power pulse, the spring loaded valve is allowed to return the valve contacting element to its normal position.
Sprays are discharged from aerosol containers in an outwardly opening conical shape. U.S. Pat. No. 3,739,944 and the other above noted patents provide for the actuating mechanism to apply force to the top of the nozzle to move a valve stem inwardly to open the aerosol valve. For example, a valve stem may initially move inwardly 0.04 to 0.045 inch before initiating the spray, and continue inward movement an additional 0.04 inch during the spray. However, such movement also moves the discharge outlet of the aerosol container with respect to an aperture in the dispenser housing. Movement between the aerosol outlet and the housing aperture presents a risk of a portion of the conical spray striking the housing about the aperture as the spray moves downwardly to thereby reduce the efficiency of the spray and cause a portion of the contents to accummulate on the housing.